1. Technical Field
The present disclosure relates to a fuel cartridge capable of supplying two fuels to an anode of a fuel cell body without using a pump, a direct methanol fuel cell having the same, and a method of purging a direct methanol fuel cell using the fuel cartridge.
2. Discussion of Related Art
Fuel cells have come into the spotlight as a pollution-free power supply system. Generation systems using fuel cells may be used as power generators in large edifices, power for electric automobiles, portable power supply, etc., and a variety of fuels, such as natural gas, city gas, naphtha, methanol, waste gas, and the like, may be advantageously used in the generation systems. All fuel cells basically operate on the same principle, and are divided, for example, into molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC), polymer electrolyte fuel cells (PEFC), phosphoric acid fuel cells (PAFC), alkaline fuel cells (AFC), and the like, depending on the electrolyte used.
Among the above-mentioned fuel cells, polymer electrolyte fuel cells are divided into a polymer electrolyte membrane fuel cell or, proton exchange membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC), depending on the fuel used. The polymer electrolyte membrane fuel cell has advantages in the electrolyte is a solid polymer that does not corrode by electrolysis or evaporate. PEMFCs also typically yield a high electric current density per unit area. In addition, the polymer electrolyte membrane fuel cells typically have very high output characteristics and a low operating temperatures compared with other kinds of fuel cells, and, therefore, have been developed as portable power supplies for automobiles, etc., distributed power sources for residences, public buildings, etc., and a small power sources for electronic equipment, etc. Direct methanol fuel cells use directly use liquid-phase fuels such as methanol without using a fuel modifier and operate at less than about 100° C., and are consequently suitable as portable power supplies or small power supplies.
Typical direct methanol fuel cells include a fuel cell body having a stack structure where a single cell and a separator are generally laminated; and a fuel cartridge for supplying a fuel to the fuel cell body. The single cell comprises a membrane electrode assembly (MEA), which comprises a polymer electrolyte membrane, and an anode electrode and a cathode electrode coupled to opposite sides of the electrolyte membrane. Direct methanol fuel cell generate electric energy by electrochemically reacting a fuel supplied to the anode electrode with oxidizing agent supplied to the cathode electrode. The fuel cell stack comprises a plurality of MEAs separated by separators. The separator is also referred to as a bipolar plate or a current collector, and functions to supply the fuel to the anode electrode through an internally mounted flow field, to supply the oxidizing agent to the cathode electrode, and to collect electricity generated at the anode electrode and cathode electrode.
However, typical direct methanol fuel cells using fuel pumps to supply fuel stored in a fuel cartridge to a fuel cell body exhibit increased volume and noise of the system and decreases the energy efficiency.
Also, in typical direct methanol fuel cell systems carbon dioxide formed at an anode of the fuel cell body may accumulated after an extended operating time, which may prevent the supply of fuel, thereby leading to a lack of the fuel thereto. In addition, water flooding at the cathode of the fuel cell body during the operation of the fuel cell can also reduce the fuel supply. In typical direct methanol fuel cell systems the anode catalyst and a cathode support may be deteriorated rapidly due to the accumulation of carbon dioxide at the anode and water flooding at the cathode when the system operates for an extended time. Accordingly, there is a need for solving accumulation of carbon dioxide at the anode and water flooding at the cathode of typical direct methanol fuel cell systems.